Atomistic calculations were performed for a slab model of the (00•1) surface of haematite, as well as for the bulk structure. In particular, the energetics of O vacancies near to the surface were studied. Atomistic modelling was used to establish the defect energies in the bulk, as a function of the distance from the surface. Transition-state calculations were performed in order to estimate barriers for several migration pathways of O vacancies in the bulk and at various depths relative to the surface. It was found that the energy barriers for several transitions were considerably lower close to the surface. Published data on the electrical conductivity and Seebeck coefficients of bulk and thin-film haematite suggested the presence of high populations of point defects near to surfaces; in agreement with the present predictions.

Defects and Charge Transport near the Hematite (0001) Surface - an Atomistic Study of Oxygen Vacancies. O.Warschkow, D.E.Ellis, J.Hwang, N.Mansourian-Hadavi, T.O.Mason: Journal of the American Ceramic Society, 2002, 85[1], 213-20